A 1.36 second occultation was recorded by Brian Loader, using video OSD technique.
Sadly there were 5 other observers registered for this event but cloud or gale prevented them observing so no clearly observed misses were recorded for this event.
View the TT14 prediction.
Observers: 1 B Loader, Darfield,NZ 2(P) Prediction, TT14 Jan 30
The circle above is plotted at the expected 13 km diameter of Tama. With only one chord it is not possible to determine whether Brian was north or south of the central line of the event.
The figure below shows the Limovie/Tangra light curve of the occultation.
There are small problems with this observation.
- The dip while very clear is only 2 sample periods long. We normally ask for at least 3 samples at the bottom to feel sure of an event.
-The predicted line does not show on the plot. Tama is small at 13 km so it should not surprise us with a rank of only 13 that it could be out of the picture even at minimum zoom. If the observation and prediction were close we might feel more confident that the dip was real and not "just noise"
- There are other single sample noise dips of similar magnitude visible in all 4 stars measured.
We should therefore be wary of using this result for astrometry.
I put these issues to Brian and his reply is:
I had, of course, one advantage in that I watched the appulse on the
monitor and "saw" the event clearly. At 16x integration it lasted well
over 1 second.
Perhaps a couple of points that should be mentioned? The drop in the light curve is close to that expected, delta mag 1.4 or 72%.
Tama is shown by Occult as having a satellite or, possibly more correctly, as a double asteroid with the "satellite" diameter given as 9km. So any event could have been due to the satellite. But the separation is shown as only 20 km, so that wouldn't bring the event significantly closer.
When we add those fators we may feel the probability is higher that this was "real", but any astrometry report should probably qualify the result as "uncertain"
Observation details for MP ( 1089 ) Tama By Star UCAC4 579-041439 On 2014-02-23 at 10:38:14.0 _______________________________ Observer B. Loader Location Darfield,NZ Longitude +172:06 Latitude -43:28 Altitude 210 m Datum WGS84 Telescope SCT including Cass and Mak Aperture 25 cm Seeing Slight flickering Clear Camera Type WAT120N+ PAL/CCIR Camera Delay -0.35 Timing GPS - time inserted Video with frame analysis Disappearance 10:38:23.40 Reappearance 10:38:24.76 Comments: Event recorded using OccuRec. Clear event for 2+ integrated frames. Times and accuracy determined by visual examination of Tangra light curve. Report prepopulated by IOTA Reporting Add-in for OW ver.1.8